1. Field of the Invention
The present invention relates to a light emitting diode package, more particularly, capable of preventing the creation of voids in resin material surrounding a light emitting diode chip or the leakage of resin material to the outside.
2. Description of the Related Art
Recently various approaches are under development to substitute various conventional light sources for illumination with a Light Emitting Diode (LED) thanks to its rapid improvement in efficiency and brightness. For the purpose of this, high brightness and power LEDs which overwhelm conventional diodes with size and input voltage are being developed and commercialized also.
One subject to be noticed is a packaging method for enabling an LED to stably operate in high brightness and power conditions. From this point of view, silicone-based resin material has been observed. The silicone-based resin material has excellent optical properties since it is resistive to yellowing, that is, change in quality induced by single wavelength light and has high refractivity. Unlike epoxy which is to be solidified, the silicone-based rein material still maintains a gel or elastomer state even after being cured, and thus can stably protect a diode against impact or vibration.
In application of silicone to an LED package, transparent silicone gel is injected with a dispenser into a space between a lens and a cup-shaped cavity of a package body where an LED chip and a lens are assembled in their order into the cup-shaped cavity of the package body.
However, the injection technique has a high probability that silicone may not completely fill up the cavity creating voids or bubbles. Further, bubbles also may be generated from gas residing between the chip and an underlying substrate or by the gravity. The voids or bubbles function as one of major factors which degrade optical properties of a final LED package.
In order to prevent the formation of voids or bubbles within a cavity, there was proposed an approach disclosed in Japanese Patent Publication No. 2003-124525 and U.S. patent application No. 2003/0067264 claiming the benefit of the former, entitled “Light-Emitting Diode and Method for Its Production.”
FIG. 1A is a sectional view illustrating an LED diode disclosed in the above documents, and FIG. 1B is an exploded view of the LED diode shown in FIG. 1A.
Referring to FIGS. 1A and 1B, an LED 10 includes an LED chip 50, a base 30 housing the LED chip 50 and a lens member 20 mounted on the base 30. The base 30 has a cup part 31 with a concave structure, and the LED chip 50 is held and mounted inside the cup part 31. The base 30 is worked into a predetermined shape for example by grinding ceramic material or molding plastic.
Wires 41 and 42 are formed on the surface of the base 30. One ends of the wires 41 and 42 are extended into the cup part 31 to form chip-connecting parts 45 and 46 for electrical connection to the LED chip 50 within the cup part 31, respectively.
The lens member 20 mounted on the base 30 is made of transparent material, and has outer and inner convex parts 24 and 25.
The resin material or chip coating material 70 is filled inside the cup part 31. Resin material 70 has the effect of adhering and anchoring the lens member 20 and preventing the deterioration of light-emitting diode chip 50.
The surface of the resin material 70 is represented by the reference numeral 71 right after the resin material 70 is filled into the cup part 31. When the lens member 20 is mounted on the base 30, the surface of the resin material 70 is changed as represented by the reference numeral 72 in FIG. 1B to match the surface of the inner convex part 25 of the lens member 20. As a result, this eliminates any hollow space that may form into voids within the cup part 31 thereby to obtain excellent sealing properties.
Further, the inner convex part 25 of the lens member 20 may be provided with a pair of grooves (not shown) for introducing a portion of the resin material 70 extruded out by the lens member 20 by which fine sealing properties may be easily achieved.
However, the above-described LED 10 of the prior art has the following disadvantages. First, if the resin material 70 is filled by an excessively large quantity, the resin material 70 may leak along the grooves (not shown) out of the LED 10 to soil the exterior of the LED 10.
Second, since the lens member 20 when mounted on the body 30 is to be pressed downward at a desired pressure until the resin material 70 is sufficiently bonded to the lens member 20, this prior art structure needs additional pressing means.